Biological toxicant



35% siiaiis s United This invention relates to a-thiocyanatoalkyl estersof aromatic carboxylic acids useful as biological toxicant. Thisapplication is a division of copending application Serial No. 789,799,filed January 29, 1959.

It is well known in the art that biological toxicant activity isunpredictable. Unexpectedly a group of new compounds which areespecially potent microbiological toxicants particularly suitable forindustrial preservative use have been found.

It is a primary object of this invention to provide new compounds whichare very potent microbiological toxicants especially useful asindustrial preservatives.

These and other objects of the invention will become apparent as adetailed description of the invention proceeds.

The new compounds of the invention are a-thiocyanatoalkyl esters ofmonocyclic aromatic carboxylic acids of the formula wherein n is aninteger from to 2 inclusive. Where it is 1 or 2, the methyl radicals canbe in ortho, meta and/ or para relationship to each other and the carbonatom of the aromatic ring attached to the carbonyl atom, i.e., suchcompounds as thiocyanatomethyl o-toluate, thiocyanatomethyl m-toluate,thiocyanatomethyl p-toluate, thiocyanatomethyl 2,3-dimethylbenzoate,thiocyanatomethyl 2,4-dimethylbenzoate, thiocyanatomethyl 2,5-dirnethylbenzoate, thiocyanatomethyl 3,4-dimethylbenzoate,thiocyanatomethyl 3,5-dimethylbenzoate. The new compounds of theinvention can be made by reacting the corresponding chloromethylaromatic carboxylic acid ester with an alkali metal thiocyanate.

Actually, broadly speaking, a-thiocyanatoalkyl esters of aromaticcarboxylic acids of the formula are active biological toxicants, R beingan aromatic radical and R a lower alkyl radical. The preferred compoundsare those in which R is a monoor bicyclic aromatic radical. The aromaticnucleus can be unsubstituted or substituted with lower alkyl radicals,preferably methyl, halogen atoms preferably bromine or chlorine, loweralkoxy radicals, nitro radicals, cyano radicals, thio cyano radicals,etc., or mixtures thereof. It is preferred that not more than 5substituent groups be contained on the aromatic nucleus. An alternativemethod of making these compounds is to react an alkali metal salt, e.g.,sodium, of an aromatic carboxylic acid with an a-halo, preferably bromo,alkylthiocyanate.

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3,141,818 Patented July 21, 1964 The new compounds of the invention areparticularly useful for the prevention and control of bacterialinfection and of decomposition and decay caused by mildew, molds, andother non-chlorophyll-containing plants. Thus, e.g., the presentproducts can be used for the protection of organic materials subject todeterioration by rotting, such as leather, fur, pulp, paper, textile,rope, rubber, latex plastics, and paint. Incorporation of protective fungis'tafs ifi suc h"organie materials is especially desirable when theyare exposed to conditions favoring microbiological growth. Thus, e.g.,the present microbiological toxicants can be used to protect wood buriedin ground, as in the case of railroad ties and telephone poles; textilesexposed to dampness, as under tropical conditions or in the case of lawnfurniture, awnings, etc.; or they can be used in marine paints andlacquers subject to algal and fungal attack, etc. The present productscan also be used as seed protectants and soil sterilants for thesuppression of organic organisms harmful to seeds and plants.Additionally the present microbiological toxicants which are activeagainst sulfate-reducing bacteria can be added to oil field injectionflood waters for the prevention of pipe plugging caused by hydrogensulfide releasing bacteria such as Desulfovibrio desulfuricans.

The microbiological toxicants of this invention also have a high degreeof germicidal activity and compositions containing these products aregood disinfectants. Disinfectant compositions containing the presentproducts can be used in the disinfection or sterilization of sur gicalinstruments, dairy equipment, eating utensils and other articlesrequiring such treatment or in sanitary cleaning solutions to washwalls, floors, etc. When employed in the manufacture of pharmaceutical,cosmetic, edible compositions, the present microbiological toxicants canhave both preservative and antiseptic effects.

The thiocyanatomethyl aromatic carboxylates of the invention can beapplied directly to the material to be treated, e.g., by incorporationof the compound in a disinfectant soap or antiseptic cream. However,because the present products are effective in extremely diluteconcentrations, for most applications it is preferred to incorporatethem in a carrier or diluent. The choice of diluent is determined by theuse of the composition as is the concentration of the active ingredientin the diluent. Thus, by admixture with an inert pulverulent carriersuch as talc, bentonite, kieselguhr, diatomaceous earth, etc., there canbe prepared compositions suitable for admixture with seeds, etc., toafford protection from microbiological attack in the soil. Solutions ofcompounds in organic solvents such as kerosene can be applied as a sprayor impregnating bath, if desired, with the use of pressure to facilitatepenetration of the solution for treatment of cellulosic materials toproduce, e.g., rot-proofing. Suitable formulations for application ofthe new products to articles subject to microbiological attack are alsoprepared by mixing the compounds with an emulsifying agent in thepresence of organic solvents and then diluting with water to form anaqueous emulsion containing the compound. Suitable emulsifying agentsinclude, e.g., alkylbenzenesulfonates, polyalkylene glycols, salts ofsulfated long-chain alcohols, sorbitan fatty acid esters, etc.; otheremulsifying agents which can be used to formulate emulsions of the newcompounds are listed, e.g., in US. Department of Agriculture BulletinE607. Aqueous emulsions of the microbiological toxicant products of theinvention are also particularly suited for use in disinfectantsolutions, e.g., to wash floors and walls, or to rinse restaurant ware,etc. In another embodiment of this invention standard paint formulationscan be used as a diluent and carrier for the microbiological toxicantcompounds of the invention; these products can assist in preventing moldgrowth in, e.g.,icasein p aints and the paints can also be applied tosurfaces" which are thereby rendered resistant to the growth of bacteriaand fungi. The microbiological toxicants can also be admixed withcarriers which are active of themselves, for example with hormones withbuffering and/ or softening agents, etc.

The invention will be more clearly understood from the followingdetailed description of specific examples thereof:

Example 1 This example illustrates the preparation of thiocyanatomethylbenzoate. To a flask with a reflux condenser was charged 17 grams (0.10mole) of chloromethyl benzoate (which can be prepared by light catalyzedchlorination of methyl benzoate as described in US. 2,816,134 or by thereaction of benzoyl chloride with paraformaldehyde), 10 grams (0.11mole) of KSCN and 125 ml. of ethanol. The reactants were heated forabout 1 hour at reflux temperature (about 75 C.) and allowed to cool. AWhite solid, which was KCl, precipitated and was filtered off. Theamount of KCl recovered was about 6.4 grams. The filtrate from thefiltration was heated under reduced pressure to remove the greater partof the solvent and gave a turbid yellow liquid residue. Upon applyingvacuum in the distillation of this liquid residue, the residuesolidified to a yellow mass, weighing 18.6 grams and having a meltingpoint of 4748 C. A sam- 'ple of 4.7 grams of this crude solidifiedproduct was recrystallized from 14 ml. of hexane and 6 ml. of benzene togive light yellow crystals having a softening point of 48 C. and amelting point of 50.551.5 C. This partially purified sample wasrecrystallized again from the same solvent to give a purified producthaving softening point of 50 C. and a melting point of 5152 C. Anitrogen analysis of this purified product showed 7.26% nitrogen.Alkaline hydrolysis, then acidification of the product gives benzoicacid, M.P. 12l122 C. This product is thiocyanatomethyl benzoate.

Example 2 For the evaluation of the bacteriostatic and fungistaticeffects of these new compounds, the product of Example 1 was chosen fortesting, namely, thiocyanatomethyl benzoate. This compound was mixed inpredetermined concentrations with hot sterile agar which wassubsequently poured into Petri dishes, cooled and allowed to harden.Nutrient agar containing the test compound was then inoculated with thebacteria Staphylococcus aureus and Salmonella typhosa and incubated for2 days at 37 C., and Sabourauds dextrose agar containing the testcompounds were inoculated with the fungus organism Aspergillus niger andincubated for 5 days at 20 C. These tests showed inhibitions of theStaphylococcus down to 100 parts per million (p.p.m.) concentration ofthe compound tested, inhibition of the growth of Salmonella typhosa downto ppm. concentration of the compound tested, and inhibition of thegrowth of the Aspergillus niger down to 1 ppm. concentration of thecompound tested. Thus, it will be seen that these compounds areextremely potent bacteriostats and fungistats. Usually these novelcompounds will be applied as bacteriostats or fungistats atconcentrations in the range of 0.0001 to 1.0%, preferably 0.001 to 0.1%,suspended, dispersed or dissolved in an inert carrier, but higherconcentrations can be used, if desired; and, in any event, themicrobiological toxicant must be present in the toxicant formulation orcomposition in at least a concentration sufficient to inhibit the growthof the bacteria and/or fungi to which it is being applied, i.e., amicrobiologically toxic amount.

To illustrate the wide field of usage of the present bacteriostats andfungistats there is appended below a table showing minimumconcentrations of thiocyanatomethyl benzoate inhibiting the growth ofvarious test organisms.

Lowest Lowest Bacteriostatic 'lest ppm. Fungistatic Test ppm. OrganismInhibit Organism Inhibiting ing growth growth Staphylococcus amen:Aspergillus niger IPC ATCC 144 1O Bacillus cereus var my- Penicilli'u'mexpansum coides IPC 509" 10 IPC 126 1 Bacterium ammon Fo'mes a'rmosusFPL ATCC 6871 100 517 1 Escherichia coli AICC Trichoderrna sp. T-l

11229 1O ATCC 9645 1U Erwinia atroscplica AT- Ceratostomella pilz'fera C7404 100 ATCC 8713 10- Salmtmella lyphosa (Hop- Aspergillus cryzae kinsstrain) 100 ATOC 10196 1 Pseudomonas aeruginosa Myrothecium verru- QMB1468 a. 1000 caria ATCC 9095 I Bacillus subtilis (Lam- Mom'liniafructicola I bert) 1 U. of Ill. I

Lenzites trabca Madison 617 I Not only are the compounds of theinvention potent microbiological toxicants but they are generally activeas biological toxicants. In tests conducted using the toxi-- cant ofExample 1, insecticidal, fungicidal, herbicidal, and nematocidalactivity was demonstrated. Thiocya' natomethyl benzoate was especiallyactive against yellow fever mosquito larvae, and was active against allstages of the 2-spotted spider mite as Well as showing residual activityagainst the spider mite in insecticidal testing. Both broad and narrowleaf contact herbicidal activity and pro-emergent herbicidal activitywas demonstrated on the testing of this compound. In fungicidal testingseveral different kinds of fungus were killed by this compound. Thethiocyanatomethyl benzoate test compound of the invention also proved tobe effective as a nematocide. For use of the compounds of the inventionother than as microbiological toxicants, the compounds would in general,be compounded in a manner similar to that for microbiological use exceptthat concentrations of the toxicant would be similar to thoseconventionally applied for these other uses; but, in any event, thetoxicant must be present in the toxicant formulation or composition inat least an amount sufficient to kill the particular biological pest orpests to which it is applied, i.e., a pesticidally effective amount.

Although the invention has been described in terms of specifiedembodiments which are set forth in considerable detail, it should beunderstood that this is by way of illustration only and that theinvention is not necessarily limited thereto, since alternativeembodiments and operating techniques will become apparent to thoseskilled in the art in view of the disclosure. Accordingly, modificationsare contemplated which can be made without departing from the spirit ofthe described invention.

What is claimed is:

1. The method of inhibiting the growth of undesired microorganisms whichcomprises exposing said microorganisms to at least an amount sufficientto inhibit their growth of a compound of the formula where n is aninteger of from 0 to 2 inclusive.

2. The method of inhibiting the growth of undesired 5 6 microorganismswhich comprises exposing said micro- 2,433,106 Flenner et a1 Dec. 23,1947 organisms to at least an amount sufiicient to inhibit their2,617,818 Mowry Nov. 11, 1952 growth of thiocyanatomethyl benzoate.2,620,290 Searle Dec. 2, 1952 2,692,889 Johnson Oct. 26, 1954 ReferencesClted 111 the fi of thls patent 5 2,796,425 Scalera et a1 June 18 1957UNITED STATES PATENTS 2,819,197 Santmyer et a1. Jan. 7, 1958 2,376,105Williams May 15, 1945

1. THE METHOD OF INHIBITING THE GROWTH OF UNDESIRED MICROORGANISMS WHICHCOMPRISES EXPOSING SAID MICROORGANISMS TO AT LEAST AN AMOUNT SUFFICIENTTO INHIBIT THEIR GROWTH OF A COMPOUND OF THE FORMULA